1. Field of the Invention
The present invention relates to a regenerative control apparatus of an electric vehicle, which is driven by a battery power generated by a motor for running the vehicle.
2. Description of the Related Art
In an electric vehicle a dynamic power of which is an electric motor, when its brake pedal is stepped on, a mechanical braking power and an electrical regenerative braking power based on the power generating effect of the motor, are applied at the same time, and the energy for the regenerative brake, that is a so-called regenerative torque, is stored in the battery power. Further, in order to achieve an appropriate braking operation, the step-on (actuating) amount of the brake pedal is detected, and the value of the regenerative torque is adjusted in accordance with a results of the detection.
For example, according to the technique disclosed in Jap. Pat. Appln. KOKAI Publication No. 47-24012, a brake force is sensed from the step-on amount of the brake pedal or the leg-power applied on the brake pedal, and a regenerative torque, which is in proportional to the brake force, is determined.
Or, according to the technique disclosed in Jap. Pat. Appln. KOKAI Publication No. 1-58203, the value of a regenerative torque is obtained by multiplying a regenerative torque command value which is set in accordance with the step-on amount of the brake pedal, with the maximum regenerative torque in accordance with the number of rotation of the motor for that step-on amount.
Or, according to the technique disclosed in Jap. Pat. Appln. KOKAI Publication No. 1-126103, a regenerative torque is determined in accordance with the operation amount of the brake operating means and the operation acceleration speed of the brake operating means.
It should be noted that there is a time lag mainly due to a mechanical factor, from the point when the braking operation is started, and to the point a regenerative torque is actually generated. If there is an excessively long time lag, the braking is delayed, whereas if there is an excessively short time lag, an excessively quick service is always obtained, resulting in an uncomfortable vehicle ride.
With the techniques of the above-described documents, a time lag between when the brake is operated and when the regenerative torque for braking is actually generated, is set always at constant, and therefore an optimum brake response cannot be obtained.